PRODUCTION OF FERROUS ALLOY PLATED STEEL SHEET EXCELLENT IN ELECTRODEPOSITION COATING PROPERTY AND WORKABILITY AND HAVING PLURAL FERROUS ALLOY PLATING LAYERS

摘要

PURPOSE:To produce a ferrous alloy plated steel sheet excellent in electrodeposition coating property and workability by forming an alloyed hot-dip iron-zinc alloy coating layer on the surface of a steel sheet, passing this steel sheet through an acid bath for the prescribed time under a nonelectrified condition, and then applying electroplated ferrous alloy coating to the above. CONSTITUTION:Hot-dip galvanizing is applied to the surface of a steel sheet 1 and then heating is performed to exert alloying, by which an alloyed hot-dip iron-zinc alloy coating layer 2 having prescribed coating weight is formed as a lower layer. This steel sheet 1 is passed through a bath containing acid bath for 1-5sec under a nonelectrified condition, by which a part of base zinc-enriched phase in the above plating layer 2 is dissolved and lots of fine ruggedness 2a is formed. Subsequently, this steel sheet 1 is passed through plural electroplating baths to undergo cathode electrolytic treatment. By this electrolysis, an electroplated ferrous alloy coating layer 3 as an upper layer is formed on the above plating layer 2 as a lower layer. By this method, the ferrous alloy plated steel sheet excellent in electrodeposition coating property and workability and having plural ferrous alloy plating layers can be obtained.